Jack Martin (Danny Kaye), an American entertainer working cabarets on the French Riviera, does an impersonation of philandering industrialist Henri Duran (Kaye, again) so convincingly that even Duran&#39s beautiful wife (Gene Tierney) is fooled by it. When Duran&#39s business interests compel him to be in London when he should be hosting a large soiree at his home, Martin is persuaded to impersonate Duran at the party. But matters threaten to get out of hand when Martin (as Duran) is confronted by several of the philanderer&#39s women, and by Duran&#39s ruthless business rival, M. Periton (Jean Murat).